The Samsung Galaxy S6 and S6 edge Review
by Joshua Ho on April 17, 2015 9:00 AM EST- Posted in
- Smartphones
- Samsung
- Mobile
- Galaxy S6
- Galaxy S6 Edge
Exynos 7420: First 14nm Silicon In A Smartphone
This generation more than any generation in recent memory has been a time of significant movement in the SoC space. We were aware of the Exynos 7420 well before it was announced in the Galaxy S6, but for the most part I expected to see Snapdragon 810 in at least a few variants of the Galaxy S6. It was a bit surprising to see Samsung drop Snapdragon SoCs completely this generation, and judging by the battery life of the Galaxy S6 it seems that Samsung had their reasons for doing this.
For those that are unfamiliar with the Exynos 7420, this SoC effectively represents the culmination of their efforts in semiconductor manufacturing and integrated circuit design. On the foundry side, Samsung is leveraging their vertical integration to make the first SoC on their 14nm LPE (Low Power Early) process, which seems to be solely for Systems LSI until they can no longer use all production capacity.
We previously mentioned that Samsung’s 14nm process in general will lack any significant die shrink due to almost unchanged metal interconnect pitch, but this assumption was in comparison to their 20nm LPM process from which the 14nm LPE process borrows its BEOL (back end of line) from. Opposite to what we thought, the Exynos 5433 was manufacturered on a 20LPE process which makes use of a quite larger metal layer. The result is that one can see a significant die shrink for the 7420 as it is, according to Chipworks, only 78mm² and a 44% reduction over the Exynos 5433's 113mm². This is considerable even when factoring in that the new SoC had two added GPU shader cores. Beyond the swap from a LPDDR3 memory controller to a LPDDR4 capable one, the only other at first noticeable major functional overhaul on the SoC seems to be that the dedicated HEVC decoder block has been removed and HEVC encoding and decoding capability has been merged into Samsung's MFC (Multi-Function Codec) media hardware acceleration block.
Galaxy S6 PCB with SoC and modem in view (Source: Chipworks)
The move from a planar to FinFET process is crucial. Although this is covered in more detail in previous articles, the short explanation is that planar processes suffer from increasing power leakage at smaller process nodes as the bulk of the silicon becomes relatively more massive than the gate that controls the flow of current. This causes decreased power efficiency as the power source of the transistor starts to act as a gate itself. FinFET solves this problem by attempting to isolate the transistor from the bulk of the silicon wafer, wrapping the gate around the channel of the transistor to ensure that it retains strong control over the flow of current compared to a planar transistor design.
The effective voltage drop allowed by the process can be substantial. We can have a look at some voltage excerpts of common frequencies available on both the Exynos 5433 and 7420:
| Exynos 5433 vs Exynos 7420 Supply Voltages | ||||||
| Exynos 5433 | Exynos 7420 | Difference | ||||
| A57 1.9GHz (ASV2) | 1287.50mV | 1056.25mV | -234.25mV | |||
| A57 1.9GHz (ASV9) | 1200.00mV | 975.00mV | -225.00mV | |||
| A57 1.9GHz (ASV15) | 1125.00mV | 912.50mV | -212.50mV | |||
| A57 800MHz (ASV2) | 950.00mV | 768.75mV | -181.25mV | |||
| A57 800MHz (ASV9) | 900.00mV | 687.50mV | -224.50mV | |||
| A57 800MHz (ASV15) | 900.00mV | 625.00mV | -275.00mV | |||
| A53 1.3GHz (ASV2) | 1200.00mV | 1037.50mV | -162.50mV | |||
| A53 1.3GHz (ASV9) | 1112.50mV | 950.00mV | -162.50mV | |||
| A53 1.3GHz (ASV15) | 1062.50mV | 900.00mV | -162.50mV | |||
| A53 400MHz (ASV2) | 862.00mV | 743.75mV | -118.25mV | |||
| A53 400MHz (ASV9) | 787.50mV | 656.25mV | -131.25mV | |||
| A53 400MHz (ASV15) | 750.00mV | 606.25mV | -143.75mV | |||
| GPU 700MHz (ASV2) | 1125.00mV | 881.25mV | -243.75mV | |||
| GPU 700MHz (ASV9) | 1050.00mV | 800.00mV | -250.00mV | |||
| GPU 700MHz (ASV15) | 1012.50mV | 750.00mV | -262.50mV | |||
| GPU 266MHz (ASV2) | 875.00mV | 750.00mV | -125.00mV | |||
| GPU 266MHz (ASV9) | 800.00mV | 668.75mV | -131.25mV | |||
| GPU 266MHz (ASV15) | 762.50mV | 606.25mV | -156.25mV | |||
The ASV (Adaptive Scaling Voltage) numbers represent the different type of chip bins, a lower value representing a worse quality bin and a higher one a better quality one. Group 2 should be the lowest that is found in the wild, with group 15 representing the best possible bin and group 9 the median that should be found in most devices. As one can see in the table, we can achieve well up to -250mV voltage drop on some frequencies on the A57s and the GPU. As a reminder, power scales quadratically with voltage, so a drop from 1287.50mV to 1056.25mV as seen in the worst bin 1.9GHz A57 frequency should for example result in a considerable 33% drop in dynamic power. The Exynos 7420 uses this headroom to go slightly higher in clocks compared to the 5433 - but we expect the end power to still be quite lower than what we've seen on the Note 4.
On the design side, Systems LSI has also done a great deal to differentiate the Exynos 7420 from the 5433. Although the CPU architectures are shared, the A53 cluster is now clocked at 1.5 GHz instead of 1.3 GHz, and the A57 cluster at 2.1 GHz rather than 1.9 GHz. The memory controller is new and supports LPDDR4 running at 1555MHz. This means that the Galaxy S6 has almost double the theoretical memory bandwidth when compared to the Galaxy Note 4 Exynos variant, as we get a boost up to 24.88GB/s over the 5433's 13.20GB/s. We still need to test this to see how these claims translate to practical performance in a deep dive article in the future, as effective bandwidth and latency can often vary depending on vendor's memory settings and SoC's bus architecture.
Outside of the memory controller, LSI has also updated the 7420 to use a more powerful Mali T760MP8 GPU. Although the Exynos 5433 had a Mali T760 GPU as well, it had two fewer shader cores which means that achieving a given level of performance requires higher clock speeds and higher voltages to overcome circuit delay. This new GPU is clocked a bit higher as well, at 772 MHz compared to the 700 MHz of the GPU in the Exynos 5433. We see the same two-stage maximum frequency scaling mechanism as discovered in our Note 4 Exynos review, with less ALU biased loads being limited to 700MHz as opposed to the 5433's 600MHz. There's also a suspicion that Samsung was ready to go higher to compete with other vendors though, as we can see evidence of an 852 MHz clock state that is unused. Unfortunately deeply testing this SoC isn’t possible at this time as doing so would require disassembling the phone.
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chizow - Saturday, April 18, 2015 - link
Yep exactly, I spend enough time tweaking my PC and at least it provides me proper tools to do so. After a few months with the S4 I just realized it wasn't worth it as the awful battery life and bloats OS made me want to just keep it in my pocket for fear of running out of juice when I actually needed it for phone functions.akdj - Sunday, April 26, 2015 - link
I'm ambidextrous. Use the 6+(personally) & Note 4 (family business of two decades). To be fair with your assessment the iPhone 5 sucked battery just as quick as the S4. At the time, comparable flagships for six months. 5S remedied it with iOS 7, but nothing like iOS 8 and the 6+'s battery size. It's physics and I'm with ya, not arguing. Just my two cents as my Note 4 with 5.0.1 is nearly identical to my 6+ with iOS 8.3 at the end of a 14-16 hour work and family day with similar usage shows similar reserves. Easily 50%. Usually high sixtiesThe memory leaks of yesterday and more granular control of apps and their background abilities on Amdroid (and the new core framework of 5.0), it's distribution of RAM (compression) and raw speed of the NAND makes the new generations of Android feel like iOS. Seriously. It's rare I run into less than 60fps manipulating the UI. And I use third party launcher Nova or Google. Samsung's stock browser is now not only capable but 'fast' and the displays have come a really REALLY LONG way since your S4. They're cool. Stop in and play with the hiDPI models like the S6 and Note 4. The latter of which hauls ass. And looking at these results, the S6 smokes it!
Across the board! And like us iOS dorks, Android's finally got a 128GB on board storage option. I'm as die hard SD card user as there is. I've got a Samsung Pro micro SD that just came out, & it screams! Awesome to pack with media and the like. But then again, I had two choices. White or black. 32 or 32GB. Even the fastest 64GB CF cards are over $200 to get to ½ the speed the S6's internals are reading and writing. And removable storage is prone to failure by user fault than non accessible OEM supplied 'system' optimized storage.
This latest batch of iOS and Android flagships have seen a significant increase in the internal read/write performance. Anyone that used or is using HDDs and have switched to an SSD knows the difference in perceived speed. It's the same on a phone when they've increased as much as they managed to in the past two years.
Especially this round. Note 4. The iPhone 6/6+. And now the king, look at those speeds on the S6. Those are insane and with the faster SoC, RAM (DDR4) and 'storage' I just talked about, along with the lollipop update and it's corresponding (massive) energy savings I've seen makes these 'phones' over the past ten months faster than computers we were using just five years ago. With higher resolution displays. Faster internet than even possible in most places then, wired! & we're getting those speeds on LTE! Wireless cell speed, increased horsepower, refined OS and leaps and bounds of improvements to AMOLED technology have made for a really tough decision which platform to go with. I'm still partial to iOS but only because of its integration and aggregation with OS X, my OS of choice. While I also use Win 8.1 and enjoy it ...neither system welcomes my browser of choice for nearly a decade. Chrome. Now 'Google Apps' it 'takes over' your computer. OS X or Windows, slow as molasses and it's a resource hog! Never thought I'd see the day IE and Safari would be my first choice(s).
Sorry to ramble. Just a view from someone not as responsible as yourself (I've no self control and can't decide between which, so both) and having continued ownership of both platforms since you switched, I'm floored by the improvements to Android, and their associated flagships. The displays are unbelievable when watching movies. Just awesome. Hard to explain how immersive a flick is on a 1440p 5.7" display with a killer set of cans ;)
Onsager - Friday, April 17, 2015 - link
Well written article, however given the few negatives, and very notable benchmarks, I am surprised it didn't receive a 'recommended' badge. The Exynos 7420 Soc itself deserves an award. In fact, numerous statements in the article certainly distinguish this phone as the current class of the field. 'What's a phone gotta do...'halcyonmax - Friday, April 17, 2015 - link
couldn't agree more.gnx - Friday, April 17, 2015 - link
+1Peichen - Saturday, April 18, 2015 - link
Is it necessary? The conclusion already states this is the best Android phone out right now.Onsager - Saturday, April 18, 2015 - link
By that rationale, no awards are ever necessary.akdj - Sunday, April 26, 2015 - link
That's kinda what I concluded. Awards? Who GAS? Hey quite honestly says this is hands down the Android 'king of the hill' (my quote) several times. Camera. Check. Display check. SoC - Yep, Whole page devoted to it eating the rest of the field for lunch. The only silicon that competes with it right now is the A8, Apple's second generation 64bit bad ass.Kinda cool Sammy did what they did with Exynos when the SD810 heat/throttling came to light. Good for them but I think I must've read a different article than you. This isn't a site for trophies and ribbons. And you don't have to read between lines
He actually says this is the BEST Android on the market and perhaps best overall phone. There's areas iOS best Android and vice versa. It's tough to say ones better than the other with 'numbers' ratings or some sort of star system. Bette to say it with words as the author (Josh? I'm sorry bud. Too lazy to look;)) has dome. It's right above this section.
It's called
"Final Words"
Babios - Friday, April 17, 2015 - link
I just had a hands on with both phones for more that an hour. Nice performance but too expensive for android phones. I am disappointed from a 1000€ phone (no sd, single sim, single speaker) and I can not feel it as a premium for that price range.You can buy a cheaper android phone that can cover your needs 99% with the 1/3 of the “Edge” price. S6 can score 70000 in Antutu but mine with 40000 is super fast in every game - application I have used.
Apple became cheaper that Samsung thats the news !!!!
magreen - Friday, April 17, 2015 - link
"As a reminder, power scales quadratically with voltage, so a drop from 1287.50mV to 1056.25mV as seen in the worst bin 1.9GHz A57 frequency should for example result in a massive 48% drop in dynamic power."It's a 33% drop in dynamic power, isnt' it?
(1287.5^2 - 1056.25^2) / 1287.5^2 = 0.327.
(The 48% number would be how much more power the higher voltage part uses than the lower voltage part, which is not the power drop.)